For a well defined field, the best text book is going to balance depth and breadth. For a research subject, you will need to read scientific papers until you re

For a well defined field, the best text book is going to balance depth and breadth. For a research subject, you will need to read scientific papers until you reach the cutting edge. For a trend in the arts, you will need to follow the trendsetters on social media until you catch up to them.